This invention relates to a hoisting device for concrete slabs and, more particularly, to an improvement of the remotely operable hoisting coupling disclosed in aforementioned copending application Ser. No. 641,529 now U.S. Pat. No. 4,017,115.
Hoisting couplings for concrete slabs are shown in such patents as U.S. Pat. Nos. 3,420,014; 3,431,012; 3,456,547; and, 3,652,118, and West Germany Pat. No. 1,961,879 of June 16, 1971. Although these patents are relevant to the state of the art, they do not disclose or suggest a structure and mode of operation of the remotely operable hoisting coupling of the present invention.
The prior art is also replete with hoisting couplings for other uses and these are exemplified by the following references of record in the aforementioned copending applications: U.S. Pat. Nos. 2,346,482; 2,948,383; 3,583,753; and, 3,698,756. Although these patents are of some significance, they do not disclose the improved remotely operable lug arrangement employed in the coupling of the present invention.